253640 has 32 divisors (see below), whose sum is σ = 605880. Its totient is φ = 95232.

The previous prime is 253639. The next prime is 253651. The reversal of 253640 is 46352.

253640 = T₁₇₀ + T₁₇₁ + ... + T₁₈₅.

It can be written as a sum of positive squares in 4 ways, for example, as 232324 + 21316 = 482^2 + 146^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 253640.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 494 + ... + 866.

2²⁵³⁶⁴⁰ is an apocalyptic number.

253640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 253640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (302940).

253640 is an abundant number, since it is smaller than the sum of its proper divisors (352240).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

253640 is a wasteful number, since it uses less digits than its factorization.

253640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 401 (or 397 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 20.

The square root of 253640 is about 503.6268459882. The cubic root of 253640 is about 63.3003213615.

Adding to 253640 its reverse (46352), we get a palindrome (299992).

The spelling of 253640 in words is "two hundred fifty-three thousand, six hundred forty".